Glass-ceramic membranes

Abstract

Disclosed are processes for preparing conductive glass-ceramic membranes and methods of using them in hydrogen or proton separation.

1. A method for preparing a glass-ceramic membrane, comprising preparing a conductive glass-ceramic comprising
 a) thermal processing a glass that contains an effective amount of a metal to achieve conductivity under a suitable atmosphere to produce a conductive glass-ceramic containing crystals in which the metal segregates to the grain boundaries of said crystals and forms an interconnected conductive network within the bulk of the glass-ceramic, or 
 b) ion exchanging a glass powder with a metal, rinsing the resultant glass powder to remove metal that did not ion exchange with the glass powder, drying the powder, and sintering the powder under forming gas to form a glass-ceramic whose crystals contain said metal, 
 and 
 forming a membrane from said glass-ceramic. 
 
     
     
       2. In a method of hydrogen or proton separation, wherein the improvement comprises separating hydrogen or a proton with a glass-ceramic membrane prepared by a method according to  claim 1 . 
     
     
       3. A method for preparing a glass-ceramic membrane according to  claim 1 , comprising preparing a conductive glass-ceramic comprising
 a) thermal processing a glass that contains an effective amount of a metal to achieve conductivity under a suitable atmosphere to produce a conductive glass-ceramic containing crystals in which the metal segregates to the grain boundaries of said crystals and forms an interconnected conductive network within the bulk of the glass-ceramic, 
 and 
 forming a membrane from said glass-ceramic. 
 
     
     
       4. A method for preparing a glass-ceramic membrane according to  claim 1 , comprising preparing a conductive glass-ceramic comprising
 b) ion exchanging a glass powder with a metal, rinsing the resultant glass powder to remove metal that did not ion exchange with the glass powder, drying the powder, and sintering the powder under forming gas to form a glass-ceramic whose crystals contain said metal, 
 and 
 forming a membrane from said glass-ceramic. 
 
     
     
       5. In a method of hydrogen or proton separation, wherein the improvement comprises separating hydrogen or a proton with a glass-ceramic membrane prepared by a method according to  claim 3 . 
     
     
       6. In a method of hydrogen or proton separation, wherein the improvement comprises separating hydrogen or a proton with a glass-ceramic membrane prepared by a method according to  claim 4 . 
     
     
       7. A method according to  claim 1 , wherein the metal is silver, palladium, copper, iron, manganese, vanadium, chromium, nickel, cobalt, platinum, or gold. 
     
     
       8. A method according to  claim 1 , wherein the metal is silver. 
     
     
       9. A method according to  claim 1 , wherein the electrically conductive glass-ceramic has a conductance >10 −4  S/cm. 
     
     
       10. A method according to  claim 1 , wherein in a) a reducing agent and/or an oxidizing agent is used during thermal processing. 
     
     
       11. A method according to  claim 10 , wherein the reducing agent is sugar and the oxidizing agent is ammonium nitrate. 
     
     
       12. A method according to  claim 1 , wherein in a) a cover and/or bubbling gas is used during thermal processing. 
     
     
       13. A method according to  claim 12 , wherein the cover and/or bubbling gas is oxygen, nitrogen or argon, or a mixture thereof. 
     
     
       14. A method according to  claim 1 , wherein in a) a sugar is used as a reducing agent in conjunction with a reducing atmosphere during thermal processing. 
     
     
       15. A method according to  claim 14 , wherein the reducing atmosphere is 5% H 2  and 95% N 2  forming gas. 
     
     
       16. In a method of hydrogen or proton separation, wherein the improvement comprises separating hydrogen or a proton with a glass-ceramic membrane prepared by a method according to  claim 15 . 
     
     
       17. A method according to  claim 1 , wherein the glass-ceramic contains 0.1% to 10% of metal. 
     
     
       18. A method according to  claim 1 , wherein the glass-ceramic contains 1% to 5% of metal. 
     
     
       19. In a method of hydrogen or proton separation, wherein the improvement comprises separating hydrogen or a proton with a glass-ceramic membrane prepared by a method according to  claim 17 . 
     
     
       20. In a method of hydrogen or proton separation, wherein the improvement comprises separating hydrogen or a proton with a glass-ceramic membrane prepared by a method according to  claim 18 . 
     
     
       21. A method according to  claim 1 , wherein the glass-ceramic is a lithium disilicate glass ceramic. 
     
     
       22. A method according to  claim 2 , wherein the glass-ceramic is a lithium disilicate glass ceramic.